1. Field of the Invention
The present invention relates to a stator vane in an axial flow compressor of a gas turbine engine, and, more particularly, to an assembly for housing an inboard end of a stator vane in an axial flow compressor which positively retains a bushing thereof against outward radial movement.
2. Description of Related Art
Axial flow compressors in gas turbine engines are known to include one or more rotor and stator stages for air to flow therethrough and be compressed. The stator stages include stator vanes which remain stationary, while the rotor stages have airfoils which are allowed to rotate. Although various mechanisms and assemblies have been developed to retain the outboard end of stator vanes with respect to compressor casings, little has been done to prevent outward radial movement of bushings or the like used to house the inboard end of stator vanes from the shroud of a compressor. Because more recent compressor shroud designs are normally made up of two axially split, 180.degree. segmented shrouds that are bolted together, reliance has been placed upon the clamp load exerted on a bushing or the like from the shroud halves about the periphery of the bushing. By relying solely upon such a clamp load, however, it has been found that the bushing has a tendency to move radially outward when subjected to engine vibratory signatures and thermal cycling during engine operation.
Radial movement of a bushing retaining the stator vane inboard end is significant since it results in an outward flowpath step which causes a deficit in engine performance. It will be understood by those skilled in the art that the outboard surfaces of the bushing and the compressor shroud comprise a compressor inner gas flowpath annulus and any obstruction thereof impacts the performance of the engine. Moreover, radial movement of the bushing frequently initiates a physical interaction between the inboard surfaces of the leading and trailing edges of the stator vane and the outboard surface of the bushing. This has resulted in bushing failure and subsequent engine ingestion of the bushing, which could cause severe compressor blading damage. Such engine ingestion would also change the frequency of the stator vane, thereby resulting in air flow separation.
Accordingly, a need exists in the art for an assembly which can house the inboard end of a stator vane in the shroud of an axial flow compressor, the components of the assembly being positively retained to prevent radial displacement.